Characterization of metamorphic assemblages and assessment of Cu-Pb-Ag-Au-Zn mobility at the Lalor deposit, Snow Lake, Manitoba
Bibliographic record
Abstract
The Lalor VMS deposit is located within the Snow Lake arc assemblage at the easternmost end of the Paleoproterozoic Flin Flon belt. A regional metamorphic event at 1.81 Ga, up to middle amphibolite facies (550˚C, 5kbar), recrystallized the mineral assemblages in the massive sulfide and hydrothermally altered rocks that are associated with the formation of VMS deposits in the area. The Lalor deposit differs from most VMS deposits in the area in that it contains low-sulfide Au rich zones that are proximal to but separate from the massive sulfide lenses. Gold mineralization primarily occurs in three rock types at the Lalor deposit: massive sulfides, and calc-silicates to carbonate silicates, and Fe-Mg altered rocks. Electrum is the dominant form of gold, but gold also occurs in sulfosalt phases such as aurostibite (AuSb2) and in tellurides such as petzite (Ag3AuTe2). It is often associated with hessite (Ag2Te), altaite (PbTe), chalcopyrite (CuFeS2), and galena (PbS). Gold mineralization occurs along fractures, grain boundaries, cleavage planes, and as discrete inclusions in metamorphic minerals. There are two dominant metal associations with gold: Cu-Au and Pb-Au. The Cu-Au association is more common and occurs in a variety of rock types (including massive sulfides and Fe-Mg altered rocks), whereas the Pb-Au association is restricted to calc-silicate to carbonate silicate altered rocks. In the massive sulfides, gold content and distribution are a function of primary VMS zone refining processes; however, Au has been locally remobilized during metamorphism and deformation. In the Fe-Mg altered rocks proximal to massive sulfide, the distribution and tenor of Au reflects primary zone refining and local remobilization due to metamorphism and deformation, whereas in Fe-Mg altered rocks distal to massive sulfide, gold distribution is largely a product of pre-peak to peak metamorphic remobilization of primary VMS gold via fluid-dominated transportation. In the calc-silicate to carbonate silicate rocks, which contained or contain carbonate, Au distribution reflects metamorphic remobilization. Metamorphic devolatilization of primary carbonate bearing rocks is responsible for adding components such as H2O, CO2 and S2 into a fluid phase that remobilized Au and some metals (e.g. Cu, Pb) in the deposit, and in altered rocks located proximal and distal to the massive sulfide lenses. Gold was mobilized and transported as a sulfur complex, with CO2 acting as a buffer for a low salinity fluid phase such that it could maintain an elevated gold content for transport and deposition. The result of this mobilization is responsible for the Pb-Au in calc-silicate to carbonate silicate altered rocks
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".